Evaporative cooling an overview sciencedirect topics. Indirect evaporative cooling can be used to lower both the dry bulb and wet bulb temperatures. Investigation of an evaporative cooler for buildings in. Let us guide you through the science of evaporative cooling. This manual is also intended as an overview of evaporative cooling principles and equipment for the nontechnical reader, with technical terms shown in bold print and defined in the glossary.
It is not only uncomfortable to work in, but it can be downright dangerous for the welfare of your workers. Riffat and zhu 12 employed ceramic materials for indirect evaporative cooling systems. Youve probably experienced the effects of evaporative cooling if youve. The concept of evaporative cooling came from the sweating of our bodies. The conversion of sensible heat to latent heat causes a decrease in the ambient temperature as water is. The results obtained for relative humidity from the greenhouses with different types of evaporative cooling pads, as well as for the conditions outside the greenhouses, at 8 am are shown in table 2 and fig. A typical recirculation cycle for the desiccant cooling system is shown in figure 21 b.
The basic design consists of a storage pot placed inside a bigger pot that holds water. Applied air offers direct evaporative cooling equipment with air deliveries from 3,000 cfm to 64,000 cfm and indirect or indirectdirect evaporative cooling units with air deliveries from 1,500 cfm to 37,500 cfm. There are two basic types of evaporative air coolers eacs used to cool new mexico schools and. Following are the two type of cooling system for engine. Principles of evaporative cooling system a pdh online. It will consist of the component parts as listed in the following sections. Evaporative cooling uses the fact that water will absorb a relatively large amount of heat in order to evaporate. Types of cooling system in engine working and advantages. Annual savings depend on the building type and the wb efficiency 21.
Humans actually use evaporative cooling naturally when they sweat as they heat up, and the sweat evaporates, lowering body temperature. Evaporative cooling design guidelines manual iv this report by nrg engineering is funded by the new mexico energy minerals and natural resources department, 1220. The science of evaporative cooling gmc airconditioning cc. This is a pdf file of an unedited manuscript that has been accepted for. An evaporative cooler is a device that cools air through the evaporation of water. Evaporative cooling is also known as swamp cooling, desert cooling and wet air cooling. Also, liquid dessicants such as lithium or calcium chloride have. There are many different styles of evaporative coolers. The cold water unit, of which a lowerperformance and therefore cheaper model can then be selected, takes over the residual or peak load. This characteristic of the process clearly establishes a measure to compare the effective water usage of various evaporative cooling processes.
Evaporative cooling systems use the same principle as perspiration to provide cooling for machinery and buildings. Evaporative cooling design guidelines ced engineering. Well, that is the principal of evaporative cooling at work in nature. Direct and indirect evaporative cooling strategies. The acceptability of different types of evaporative cooling system. Evaporative cooling ec, also known as swamp cooling, is a strategy for cooling air that takes advantage of the drop in temperature that occurs when water thats exposed to moving air begins to vaporize and change to gas. Evap pads are made of a specially formulated cellulose paper. Evaporative cooling design guidelines manual iv this report by nrg engineering is funded by the new mexico energy minerals and natural resources department, 1220 south st.
The process is indicated in the psychrometric chart below. This phase change requires energy, which is called latent heat of evaporation this is the energy required to change a substance from liquid phase to the gaseous one without temperature change. The rate of evaporative cooling is a function of both humidity and air movement. Extreme heat and humidity can, and frequently does, cause heat strokes. The analysis of variance showed that there were significant differences p 0. Dristeem evaporative cooling and humidification systems 3 how do first costs and energy costs of evaporative cooling systems compare. View evaporative cooling research papers on academia. Therefore, the evaporative cooling should be regarded mainly as a basic environmental system for pre cooling of the outside air. And the simple answer is its happening or whats allowing your body to cool the chemical process, i guess you could say the physical process is happening is evaporative cooling. Evaporative coolers can be employed as a compact and often the sole cooling system in a home. When warm, dry unsaturated air is pulled through a watersoaked pad, water is evaporated and is absorbed as water vapor into the air. Course contents evaporative coolers, often called swamp coolers, are cooling systems that use only water and a blower to circulate air.
The air system is used in the engines of motorcycles, scooters, aeroplanes and other stationary installations. In the hvac industry, the term cooling tower is used to describe both open and. Evaporative cooling, effectiveness, performance, energy saving. Thus, this type of airconditioning is neither sustainable nor. Evaluation of evaporative cooling systems in industrial buildings article pdf available in international journal of heat and technology 333. Analysis of advanced solar hybrid desiccant cooling. However, one should avoid simultaneously operating conventional air conditioners along with direct evaporative coolers. Furnish proof satisfactory to the owner or his representative, of. What is data center evaporative cooling swamp cooling. The principle of evaporative cooling reveals that the evaporative cooling system can only remove room sensible heat.
Modern technology has dramatically increased the efficiency and effectiveness of evaporative cooling system. This is placing great pressures on an electric grid that must. The greenhouse with sliced wood pads gave the lowest relative humidity 39. As shown, rh increased from 21 to 91% and w increased from 3. Typically a 1kw evaporative cooling system can manage a 20kw load. His theory of adiabatic saturation and the standard psychrometric chart are its roots. In summary, evaporative cooling is the process of removing heat from a surface due to the evaporation of water.
From the traditional central cooling system to the window air units some homeowners use, each method has its own drawbacks and advantages. Water can absorb a lot of heat without changing phases, allowing it to remove heat. This system is the oldest and the simplest type of evaporative cooling in which the outdoor air is brought into direct contact with water, i. Experts say that in germany approximately 10% of the roughly 25,000 new hvac systems produced each year are equipped with this environmentally friendly cooling technology, and that this trend is increasing. Some examples of evaporative cooling designs are described below. In a desiccant cooling system, air can be passed over common solid desiccants such as zeolite or silica gel for dehumidification and to sensibly cool the air well below ambient temperature conditions in some form of evaporative cooling process. International journal of engineering research and general. Evaporative cooling market growth, trends and forecast 2020 2025 the market is segmented by type of cooling direct evaporative cooling, indirect evaporative cooling, and twostage evaporative cooling, application residential, commercial, and industrial, distribution channel big box retailers, hvac contractors, and distributors, and region. It is used in data center and large it facilities to provide air cooling conditioning services. I wont go into the details of what types of molecules these are, but then if you have your water molecules here, water molecules that are sitting on the surface, and im drawing this is kind of a crosssection. In direct evaporative cooling sensible heat energy. Evaporative cooling market growth, trends and forecast.
Evaporative cooling pads that are saturated with water, a substantial cooling effect is realized due to the evaporation of that water. Highpressure system first costs are generally higher than other adiabatic systems due, mostly, to the cost of adding. Principles and application of evaporative cooling systems. Many households use conventional cooling systems as a backup to their evaporative cooling systems during these periods. Anyone who has spent some time in a hot, stuffy warehouse understands how torturous heat and humidity can be.
The systems design was based upon the humidifying capacity of an ultrasonic humidifier supplied by a quebec company, plastique frapa inc. Evaporative cooling systems can significantly lower the outside air temperature, even in humid climates, and improves the ability of the ventilation air to reduce the heat in the area. Greenhouse cooling systems and models for arid climate. Types of evaporative coolers direct evaporative coolers use a fan to pull outside air through media pads that are kept. Evaporative air cooling is an environmentally friendly and energy efficient method of cooling air using water as cooling medium. Applied air offers direct evaporative cooling equipment with air deliveries from 3,000 cfm to 64,000 cfm and indirect or indirectdirect evaporative cooling. Installing an evaporative cooling system is an alternative method of using an air conditioning system that pumps refrigerant through compression and evaporative cycles. The only significant energy use is in the fan for the air movement.
Evaporative cooler engineering specification 598 1. Indirect evaporative cooling heat and mass transfer research heat and mass exchanger effectiveness energy ef. A heat section can be added to most models to provide a ventilation unit for year round use. Evaporative cooling is a physical phenomenon in which. Portable coolers cool small places or rooms, generally up to 300 square feet. Used in conjunction with coolair fans, a temperature reduction of 1025 degrees is commonplace. One must know them to understand the operation of evaporative coolers.
A non recirculating evaporative cooling process would be running at 10 cycles of concentration if the feed is 10 gpm, evaporation is 9 gpm, and the bleed is 1 gpm. When low output is required, the pumpmotor is turned. Musa 11 also investigated the use of more common aspen pads materials for indirect evaporative cooling system. Design of new evaporative cooler and usage of different. Leadership in energy and environmental design leed points can be achieved by using cooling options that operate more ef. Direct evaporative cooling is designed to cool the air by evaporating water which. The direct evaporative cooling process in a psychrometric chart air at with dry bulb temperature 70 o f and relative moisture 60% state a is cooled down state b by evaporating water.
However, when the desiccant cooling system must handle the entire load, it overdries the process air so evaporative cooling can be used for the sensible cooling. Evaporative cooling is based on the thermodynamics of evaporation of water, i. Spray humidifiers deliver moisture to an atmosphere using either high pressure or compressed air to ensure evaporation. An evaporative cooler also swamp cooler, swamp box, desert cooler and wet air cooler is a device that cools air through the evaporation of water. With respect to cooling, no longer are plants being built with oncethrough cooling systems but rather the choice is either a cooling tower or aircooled condenser. The design will depend on the materials available and the users requirements. Suited for virtually all geographic locations, the. Evaporative cooling food and agriculture organization of. The same principle can be used to bring the air temperature down in warm climates. Suited for virtually all geographic locations, the coolair evaporative cooling system. Evaporative coolers have started to gain a lot of attention in the media due to its ability to provide cooling solutions for both residential and commercial applications.
Evaporative cooling is a cooling technique which uses the evaporation of water to lower the temperature. The evaporative cooling module shall be selfcontained. In central hvac systems, cooling systems based on indirect evaporative cooling are becoming increasingly important. When you are in the process of choosing a cooling system for your new home, you will come across an array of different options. Ware houses or garages, and it may also be used outofdoors on portico or on work sites.
Evaporative cooling as an efficient system in mediterranean region. Direct evaporative precooling model and analysis info oak. The evaporative cooling pad evaporative cooling pads evap pads are a product developed for horticultural and agricultural cooling applications. Concept of evaporative cooling evaporative cooling is the process by which the temperature of a substance is reduced due to the cooling effect from the evaporation of water. It is a reliable method and requires minimum power consumption. When sweat evaporates from the skin, a large amount of heat is required. While an evaporative cooling system can effectively meet the objectives of comfort cooling, it usually does not eliminate the need for airconditioning except in certain arid and dry climates. Pot designs these are simple designs of evaporative coolers that can be used in the home. A cooling tower is a heatrejection device, which discharges warm air from the cooling tower to the atmosphere through the cooling of water. Performance evaluation of three different types of local. But you probably have wondered, well, how does this work. Choosing an evaporative cooling system offers a substantial energy cost savings. Investigation of an evaporative cooler for buildings in hot.
Evaporative cooling differs from typical air conditioning systems, which use vaporcompression or absorption refrigeration cycles. A direct evaporative cooling system is the simplest and most popular evaporative cooling system available. Air cooled system is generally used in small engines say up to 1520 kw. They can also be used in combination with a regular air conditioner system. Technology, markets, and economics larry kinney, southwest energy efficiency project abstract the southwest is growing rapidlya 37% increase in population is projected from 2000 to 2020 versus 16% for the total us. Evaporative air cooling can be categorized as direct, indirect and two stage system.
Thus, it can be shown that evaporative cooling converts. Using a control system to minimise energy usage of fans coupled with evaporative cooling, relatively low flow rates of air are required. The design will depend on the materials available and. Greenhouse cooling systems and the evaluation thereof are especially relevant to the south african arid climate and for providing a solution to the problems experienced as a result of overheating. The theory of direct evaporative cooling owes much to dr. Duan, zhiyin 2011 investigation of a novel dew point. Evaporative cooling is a reliable, lowtech method to provide cooler air during hot weather. It takes heat energy to change the water or any liquid from a liquid into a vapor. It is a wellknown fact that evaporative cooling mechanism is natural, ecofriendly and involves minimal energy consumption for air conditioning. You can duplicate the principle behind direct evaporative cooling by wrapping a wet handkerchief around your neck on a hot day and standing in front of a fan. Evaporative cooling is a type of environment cooling techniques that cools the surrounding air using water evaporation technique.